Health Secretary Matt Hancock said the Government’s assessment of the Covid-19 pandemic has “not substantially changed” after a data error caused thousands of positive cases to be missed out the total figures.
But in a statement he told the Commons: “This incident should never have happened.”
On Sunday it emerged that nearly 16,000 cases had not been transferred to the test-and-trace system, sparking fears that people could have unknowingly come into contact with an infected person.
The error is believed to have been caused by an Excel spreadsheet containing lab results reaching its maximum size, and failing to update.
Security experts said they were “dumbfounded” at the use of Excel for a job as important as Covid data gathering.
Addressing the House, Mr Hancock said the spreadsheet was part of a “legacy” Public Health England computer system, and a replacement had been commissioned in July.
He said: “This morning the Joint Biosecurity Centre (JBC) presented to me their updated analysis of the epidemic based on the new figures.
“The chief medical officer (Chris Whitty) has analysed that our assessment of the disease and its impact has not substantially changed as a result of these data.
“The JBC has confirmed that this has not impacted the basis on which decisions about local action were taken last week. Nevertheless, this is a serious issue that is being investigated fully.”
He added: “I want to reassure everyone that every single person that tested positive was told that result in the normal way in the normal timeframe.
“They were told that they needed to self-isolate, which is of course now required by law.
“However, these positive test results were not reported in the public data and were not transferred to the contact tracing system.
“This incident should never have happened but the team has acted swiftly to minimise its impact, and now it is critical that we work together to put this right and make sure it never happens again.”
Responding to Mr Hancock, shadow health secretary Jonathan Ashworth accused the Government of “failing on the basics” on testing.
He said: “The Prime Minister told this House on 20th May we would have a world-beating system in place by June, it’s now October. The system is neither competent nor improving, problems are getting worse.
“The Government is failing on the basics, when will he finally fix this mess?”